[Show abstract][Hide abstract] ABSTRACT: INTRODUCTION: Corn tassel was tested as a low cost adsorbent for the removal of malachite green from aqueous solution in batch adsorption procedure. MATERIALS AND METHODS: The adsorption experiments were carried out as a function of solution pH, initial dye concentration, contact time, and temperature. The adsorption was found to be strongly dependent on pH of the medium. RESULTS AND DISCUSSION: The Freundlich isotherm model showed good fit to the equilibrium adsorption data. The mean free energy estimated from the Dubinin-Radushkevich model indicated that the main mechanism governing the sorption process was chemical ion exchange. The kinetics of adsorption followed the pseudo-second-order model and the rate constant increased with increase in temperature indicating endothermic nature of adsorption. CONCLUSION: The Arrhenius and Eyring equations were used to obtain the activation parameters such as activation energy, and enthalpy, entropy, and free energy of activation for the adsorption system. Thermodynamic studies suggested the spontaneous and endothermic nature of adsorption of malachite green by corn tassel.
Environmental Science and Pollution Research 01/2012; 19(5). DOI:10.1007/s11356-011-0723-x · 2.83 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Ulva gigantea (Kützing) bliding (UGB) obtained from sea inlet of Izmir-Turkey has been studied as a biosorbent for removal of radioactive
metals from water. In this study, unmodified UGB and modified UGB with glutaraldehyde (GUGB) characterized by FTIR spectroscopy
were used as biosorbents for removal of U(VI) and Th(IV) ions from aqueous solution. Adsorption experiments performed under
batch process with initial pH, contact time, adsorbent mass and temperature as variables. In order to determine the adsorption
characteristics, Langmuir, Freundlich and Dubinin-Raduschkevich adsorption isotherms were applied to the adsorption data.
Adsorption experiments showed that the adsorption isotherms correlated well with the Freundlich model. The sorption followed
pseudo-second-order kinetics. The thermodynamic parameters such as variations of ΔH°, ΔG° and ΔS° were estimated as a function of temperature. The thermodynamics of the adsorption of U(VI) and Th(IV) onto UGB and GUGB
indicates that the spontaneous and exothermic nature of the process. The results showed that UGB and GUGB were potential for
application in removal of U(VI) and Th(IV) from aqueous solution.
Journal of Radioanalytical and Nuclear Chemistry 06/2011; 288(3):867-874. DOI:10.1007/s10967-011-1010-5 · 1.03 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Montmorillonite KSF and K10 were used as precursor materials for synthesis of aluminum pillared K10 and KSF (Al-K10 and Al-KSF) which characterized by TGA, XRD, SEM and FT-IR spectroscopic analysis. The sorption of trimethoprim (TMP) which is commonly employed as an antibiotic onto Al-K10 and Al-KSF was also investigated as a function of adsorbent dosage, solution pH, contact time and temperature. The adsorption kinetics was interpreted using pseudo-first-order, pseudo-second-order kinetic models and intraparticle diffusion model. The pseudo-second-order model provided the best correlation. Adsorption isotherm parameters were obtained from Freundlich, Langmuir and Dubinin–Radushkevich (DR) isotherm models. Adsorption of TMP onto Al-K10 and Al-KSF was physical in nature and ion-exchange mechanism for DR equation, respectively. Al-K10 exhibits higher removal capacity at lower adsorbent dosages in comparison with Al-KSF. The removal capacity was increased by increasing pH. ΔH0, ΔS0 and ΔG0 showed that adsorption of trimethoprim was endothermic, increasing randomness and not spontaneous in nature.
[Show abstract][Hide abstract] ABSTRACT: Pillared clay-based superabsorbents (PILC-SA) were synthesized by using Al pillared-montmorillonite K10 and KSF via graft
copolymerization reaction of acrylic acid (AA). Swelling behavior of pillared clay-based superabsorbent films in distilled
water and at different pH values were investigated at room temperature. It was also obtained that Al-KSF and Al-K10 based
superabsorbents were pH dependent and showed a reversible swelling behavior. Water absorbency of Al-KSF based superabsorbent
was higher than that of Al-K10 based one. SEM, FTIR, and XRD analysis were conducted for further characterization of the PILC-SA.
FTIR analyses lead to ester formation between PILC and SA. XRD revealed the basal spacing of the pillared clays before and
after in situ incorporation indicating that the morphology of the superabsorbent was exfoliated and the layers of clay dispersed
on the composite.